From mboxrd@z Thu Jan  1 00:00:00 1970
From: gd1100@gmail.com (Grzegorz Dwornicki)
Date: Tue, 27 Jan 2015 17:49:33 +0100
Subject: No subject
Message-ID: <CAOP-CUcBEEqnX8SvZtyVm2rExCYR1Mz_qB0hNU3aHTHcz4n2Vw@mail.gmail.com>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

Keepalive question

Hello

I am bothered with very simple situaction. Lets say we have a TCP connection:

S1 <----> S2

Lets assume that this connection is using blocking sockets. and that
both hosts: s1 and s2 are using SO_KEEPALIVE. If they both are not
using this connection then the kernel? is sending packets with no data
to keep connection alive.

I have marked "the kernel?" because I am not sure who does this. I
think its the kernel but I am not sure.

What would happen if only one of them would use keepalive? Could that
empty packet break the loop inside of sk_busy_loop function and return
empty data to the application layer? Or would that while loop body
just re-run?

Hehe is the code (the while loop starts on 128 line)
http://lxr.oss.org.cn/source/include/net/busy_poll.h?a=arm#L95